This is similar to a situation where the state of New York requires that their state tax returns must be e-filed. But in NY there is a caveat in the requirement where if the software being used will not allow the state return to be e-filed, the state will accept a mailed tax return.
Unfortunately I have not seen anything in the Georgia code or instructions where a series 100 GA tax credit is allowed to be mailed if the software being used will not allow e-filing. The only thing that can be done is to call the GA Department of Revenue and see if they can recommend a solution - https://dor.georgia.gov/contact-us
